MD_DataIdentification

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Component

Title

Abstract

1

Bar Harbor, Maine Coastal Digital Elevation Model

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital
elevation models (DEMs) for select U.S. coastal regions. These integrated bathymetric-topographic
DEMs are used to support tsunami forecasting and warning efforts at the NOAA Center
for Tsunami Research, Pacific Marine Environmental Laboratory (PMEL). The DEMs are
part of the tsunami forecast system SIFT (Short-term Inundation Forecasting for Tsunamis)
currently being developed by PMEL for the NOAA Tsunami Warning Centers, and are used
in the MOST (Method of Splitting Tsunami) model developed by PMEL to simulate tsunami
generation, propagation, and inundation. Bathymetric, topographic, and shoreline data
used in DEM compilation are obtained from various sources, including NGDC, the U.S.
National Ocean Service (NOS), the U.S. Geological Survey (USGS), the U.S. Army Corps
of Engineers (USACE), the Federal Emergency Management Agency (FEMA), and other federal,
state, and local
government agencies, academic institutions, and private companies. DEMs are referenced
to the vertical tidal datum of North American Vertical Datum of 1988 (NAVD 88) and
horizontal datum of World Geodetic System 1984 (WGS84). Grid spacings for the DEMs
range from 1/3 arc-second (~10 meters) to 3 arc-seconds (~90 meters).

Not to be used for navigation. Although these data are of high quality and useful
for planning and modeling purposes, they are not suitable for navigation. For navigation,
please refer to the NOS nautical chart series.

While every effort has been made to ensure that these data are accurate and reliable
within the limits of the current state of the art, NOAA cannot assume liability for
any damages caused by any errors or omissions in the data, nor as a result of the
failure of the data to function on a particular system. NOAA makes no warranty, expressed
or implied, nor does the fact of distribution constitute such a warranty.

2

These data not to be used for navigation. Although these data are of high quality
and useful for planning and modeling purposes, they are not suitable for navigation.
For official navigation products, please refer to the U.S. nautical charts available
from the NOAA Office of Coast Survey: http://www.nauticalcharts.noaa.gov.

Datasets were visually inspected with ArcGIS and Quick Terrain Modeler for identification
and editing of data anomalies. Datasets were then compared with overlapping datasets
to ensure data consistency.

1

2011-06-24T00:00:00

Coastline datasets were merged and adjusted to fit most current lidar topographic
zero elevation line.

1

2011-07-30T00:00:00

xyz files of the bathymetric data were surfaced using GMT's 'surface' tool onto a
1 arc-second grid that interpolated to fill empty cells. Points extracted every 10
meters along the coastline were also included to ensure that the bathymetric grid
reached zero at the coast. The resulting Arc ASCII grid was imported into ArcGIS and
clipped to the coastline to remove values over land.

1

2011-08-15T00:00:00

xyz files for each input dataset were gridded using MB-System's 'mbgrid' tool, which
utilizes a high-tension spline interpolation method to fill grid cells with no input
elevation values. Preferential weighting was given to more recent, higher-accuracy
datasets.

1

2011-08-20T00:00:00

The DEM was quantitatively evaluated by comparing it with source datasets and with
elevation values extracted from NGS geodetic monuments. It was visually evaluated
by converting to UTM-zone coordinates (units of meters horizontally and vertically)
and then creating a slope grid to identify gridding artifacts in the DEM.